1. Field of the Invention
The present invention relates to rendering, and more particularly, to a 3-dimensional (3D) graphics accelerator performing rendering in a pipeline fashion.
2. Description of the Related Art
When performing rendering (i.e., visualization) of a model formed with a plurality of vertexes, a conventional rendering apparatus sequentially receives inputs of plurality of fragments generated in each plane formed by vertexes, and executes a plurality of graphic jobs for each of the input fragments. In this case, the graphics jobs may include one for expressing a fragment as a pixel, such as texture mapping, or one for testing whether or not a fragment can be expressed as a pixel, such as a depth test. The texture mapping is mapping a color value and transparency value of one location on a texture image which is a 2D image indicating material or texture, onto a fragment. The depth test is testing whether or not a fragment desired to be expressed can be expressed as a pixel, by comparing the depth value of the fragment desired to be expressed as a pixel, with a depth value which is prepared in advance for a matching location where the desired fragment can be expressed.
This conventional rendering apparatus performs the graphics job for testing whether or not a fragment can be expressed as a pixel, after performing texture mapping of the fragment. Accordingly, the conventional rendering apparatus unnecessarily performs texture mapping for even a fragment which would prove to be inexpressible as a pixel, thereby causing problems in managing efficient power consumption and fast rendering. This problem is more serious when more fragments that cannot be expressed as a pixel are included in fragments of any one model input to the conventional rendering apparatus.